Yield of Hyperventilation and Other Activation Procedures and Study Parameters in Facilitating Epileptiform...

Hyperventilation (HV) during EEG was restricted during the COVID-19 pandemic. The authors compared EEGs with and without HV to place HV in context of other factors that precipitate epileptiform abnormalities (EA). The authors hypothesized HV would not significantly affect the sensitivity of routine EEG in children and adults.

The authors reviewed routine EEGs completed between March 2018 and March 2022 in subjects older than 4 years. The primary outcome variable was EA (seizures and epileptiform discharges). In a subset of patients with serial EEGs with and without HV, the authors compared intrasubject appearance of EA (McNemar test). The authors then evaluated regression models with the outcome of EA (present or absent) against independent variables of HV, EEG duration, photic stimulation, sleep deprivation, sleep, and patient-related variables of age, sex, and anti-seizure medication burden.

Of 659 patients (806 EEGs), 180 had EA (27%). No adults had HV-activated EA. 64 of 659 patients (9.7%) had repeated EEGs both with and without HV; 34 of these (53%) had EA with HV, and 26 (41%) had EA without HV (P = 0.077, McNemar test). anti-seizure medication burden, longer recording, and HV all had significant positive odds ratios on the prevalence of EA. Sleep deprivation had a positive nonsignificant odds ratio.

Sleep deprivation, longer recording, and HV favored EA after accounting for age and epilepsy severity. Because no adults had EA with HV, the findings suggest that HV in adults can be an elective activation procedure during EEG; sleep deprivation and longer duration recordings, in contrast, provide increased yields of EA.